Summary

The same result could be obtained even the varus deformity was over 15 degrees if the case were within the indication.

Abstract

Introduction

Over half of all Osteoarthritis of the Knee can be operated by UKA safely. Long term result is not bad compared with TKA. On the contrary satisfaction rate is far better than TKA. However UKA tends to be applied for only light deformity. Satisfaction is formed from the difference between preoperative condition and postoperative one. Safety after surgery is studied when "UKA" is applied to highly deformed patients whose Hip - Knee - Ankle angle(HKA) exceeds 15 degrees.

Methods

Indication for UKA is the anterior osteoarthritis of the knee. The medial joint space can be opened by valgus stress and ACL is intact. From 2005 to 2017, patients who met this UKA indication were 1082 knees in our Center. The minimum follow-up period is 2 years after surgery.
The average age of the patients was 75 years old (ranged from 55 to 94). 398 were males and 684 were females. The patients more than 15 degrees of varus in HKA was 385 (35.6% ; defined as group V)). The other less than 15 degrees was 697 (64.4%; defined as group N). The clinical result was compared between two groups.

Results

  The dislocation of the insert was occurred 2 cases in each group. Total dislocation was 4 (0.546%). No statistical significant difference was observed by chi-square testing (P=0.491). Tibia fracture was occurred 8 in group V and 5 in group N. Total fracture after UKA was 13 (1.2%). No statistical significant difference was observed by chi-square testing (P=0.049). Loosening of the tibia tray was observed 5 in group V and 6 in group N. Total tibia loosening was 11 (1.0%). No statistical significant difference was observed by chi-square testing (P=0.491). Superficial infection was occurred in 3 in group V and 7 in group N. Total superficial infection was 10 (0.9%). 5 of them needed a further operation to wash and exchange the bearing. However all implants of the 10 infections were survived. There were no deep infection. No statistical significant difference was observed by chi-square testing (P=0.711). 7 lateral osteoarthritis progression after UKA were observed only in group N but group V. Group N had more tendency to lateral OA progress than group V by chi-square testing (p=0.034).

Discussion And Conclusion

No statistical significant difference in sever complication was observed in two groups. However lateral progress of osteoarthritis after UKA was observed in only group N. 3 of 7 lateral progression were concerned with a rheumatic onsets after the surgery. The same result could be obtained even the varus deformity was over 15 degrees if the case were within the indication.